In blow molding machines of the wheel type, a wheel supports a plurality of circumferentially spaced sets of molds and is generally rotated about a horizontal axis. Plastic tubing is continuously extruded downwardly between the open mold sections and then the molds are closed as they move about an annular path and the portion of the tubing within the molds is blown within the confines of the mold to provide a hollow article which may be a container.
In the blow molding machine shown and described in U.S. Pat. No. 4,549,865, incorporated herein by reference, the blow molding apparatus comprises a wheel plate, a shaft extending horizontal and supporting the wheel plate for rotation and a hub removably mounted on the shaft for rotation with the shaft, and a plurality of sets of molds defining a mold cavity when closed, each set comprising a pair of mold sections, a first mold section of each set being mounted on the hub such that the mold sections are circumferentially spaced about the hub, a second mold section of each set being mounted on the wheel in circumferentially spaced relation and radial alignment with the first mentioned mold section. The second mold sections are mounted on slide assemblies for movement toward and away from the first mold sections. The hub has circumferentially spaced external surfaces for supporting the first mold sections, the number of surfaces corresponding to the number of first mold sections. The hub may be removed and a second hub replaced on the shaft, having a plurality of circumferentially spaced surfaces, the number of the surfaces of the second hub differing from the number of surfaces on the first hub. The wheel plate accommodates a different number of slide assemblies to correspond with the different number of mold surfaces on the second hub.
Such apparatus has been proven to be commercially successful. However, the use of the polygonal hub, having a predetermined number of mold mounting surfaces, limits the number of mold assemblies and the size of the mold assemblies such that the hub must be removed and replaced when substantially different mold assemblies either in number or size are to be used.
Among the objectives of the present invention are to provide a blow molding machine wherein the process of changing the number of mold assemblies is facilitated by not requiring a change in the hub.
In accordance with the invention, a blow mold mounting apparatus are provided for the mold assemblies which provide for a quick changing of the number of molds and size of the molds. More specifically, the mounting arrangements comprise a flat upper surface for supporting the mold assemblies and a cylindrical lower surface that conforms with the shaft of the blow molding machine.